CO₂-Laser Induced Hot Electron Magneto-Transport Effects in n-InSb

Description

The effects of optical heating via infrared free carrier absorption on the electron magneto-transport properties of n-InSb at helium temperatures have been studied for the first time. Oscillatory photoconductivity (OPC) type structure is seen in the photon energy dependence of the transport properties. A C0₂ laser (hω = 115 to 135 meV) was used as the optical source. Concentrations between 1 x 10¹⁵ cm⁻³ and 2 x 10¹⁶ cm⁻³ were studied. The conclusions of this study are that the energy relaxation of high energy photoexcited electrons, generated by free carrier absorption of C0₂ laser radiation in degenerate n-InSb at liquid ...
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Degree Information

Description

The effects of optical heating via infrared free carrier absorption on the electron magneto-transport properties of n-InSb at helium temperatures have been studied for the first time. Oscillatory photoconductivity (OPC) type structure is seen in the photon energy dependence of the transport properties. A C0₂ laser (hω = 115 to 135 meV) was used as the optical source. Concentrations between 1 x 10¹⁵ cm⁻³ and 2 x 10¹⁶ cm⁻³ were studied. The conclusions of this study are that the energy relaxation of high energy photoexcited electrons, generated by free carrier absorption of C0₂ laser radiation in degenerate n-InSb at liquid helium temperatures, is by emission of a maximum number of optical phonons, and that this relaxation mechanism produces OPC type structure in the photon energy dependence of the electron temperature of the conduction band electron gas. This structure is seen, therefore, in the transport properties of the sample, including the Shubnikovde Haas effect, the effective absorption coefficient, and the photoconductivity (mobility) response (lower concentrations only). In addition, the highest concentration studied, nₑ = ~2 x 10¹⁶ cm⁻³, sets an experimental lower limit on the concentration at which electron-electron scattering will become the dominant energy relaxation mechanism for the photoexcited electrons, since OPC effects were present in this sample.

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